PHILADELPHIA (CBS) — A Wharton School professor’s new book on young people’s attitudes about parenthood finds that a lot more of them aren’t interested.

Management professor Stewart Friedman has been studying his own students for a generation and collects the results comparing his findings between 1992 to 2012 in the book Baby Bust, New Choices for Men and Women in Work and Family.

In 1992, his survey found, 78 percent of respondents said they planned to have or adopt children. In 2012, that dropped to 42 percent.

Friedman says young men worry they can’t be both the help-at-home dad they want to be and the 72-hour-a-week employee their boss will expect them to be, and that women want careers, friends, and to make a positive mark on the world.

“What I see is that men and women are making more conscious choices about how they want to live. Women no longer feel compelled to take that mindless march into motherhood that virtually every generation prior to this one felt compelled to do.”

(Prof. Stewart Friedman. Photo provided)

Prof. Friedman (right) says that among developed nations, the US is way behind in terms of support for child care, and family and medical leave. Such help, he believes, could help young couples to take the jump to parenthood.